Apparatus and method for selective electrolytic metallization/deposition utilizing a fluid head

ABSTRACT

A transport system for the implementation of electrolytic deposition, coating or etching; and more particularly, an apparatus for selective electrolytic metallization and deposition utilizing a fluid head arrangement. A method is provided for making and maintaining an electrical contact with a product being processed in a transport system employed for selective electrolytic metallization and deposition, coating or etching. The method of making and maintaining an electrical contact with a product being processed may be utilizing a fluid head arrangement.

BACKGROUND OF THE INVENTION

1. 1. Field of the Invention

2. The present invention relates to a transport system for theimplementation of electrolytic deposition, coating or etching; and moreparticularly, relates to an apparatus for selective electrolyticmetallization and deposition utilizing a fluid head arrangement. Theinvention is also directed to a method of making and maintaining anelectrical contact with a product being processed in a transport systememployed for selective electrolytic metallization and deposition,coating or etching. Furthermore, the invention is also directed to amethod of making and maintaining an electrical contact with a productbeing processed as described herein, utilizing a fluid head arrangement.

3. A critical feature of any electrolytic process, particularly such asmay be employed for the electrolytic metallization or deposition ofmetallic materials on a substrate is to be able to make good electricalcontact with hardware on the substrate; for example, such as circuitboards, which are to be processed through the electrolytic metallizationand deposition operation. In some instances, in order to implement theforegoing there is employed a type of well known apparatus employing aso-called fluid head design, incorporating electrodes which can beactivated for implementing the metallization and deposition processes.Ordinarily, a fluid head does not readily enable the processing ofdiscrete structures or product which are transported in separate partsor piecewise, but rather is adapted for processing continuous foils orwebs forming the substrate, but which will still maintain electricalcontact with each part. Processing with a fluid head is normallyconsidered to be better suited to the implementing of reel to reelapplications of the electrolytic metallization and deposition process,where a communing bar can be fabricated within the roll or web ofmaterial which is to be processed. However, without the capability ofproviding a continuous electrical contact, these processes areimpossible to implement within the construction or format of a fluidhead for individual printed circuit board processing.

4. Basically, conventional vertical or horizontal electrolyticmetallization devices typically handle a standard, and very specific,size panel, in essence, a substrate, for their everyday production. Whenthe size of the panel varies, especially in connection with processingwith horizontal devices, ordinarily the device has to be shut down andthe electrodes baffled so that the “active” area is retained within thesize of the panel which is to be transported. This activity requiresthat the device be shut down completely, opened up and modified which,in turn, has to be then implemented a second time in order to return tothe original panel size. This results in a significant amount ofnon-productive downtime, as well as requiring engineering supervision.On panels with varying circuit densities, if processed by means ofelectro-pattern plating, there are also encountered problems withvarying thickness in the deposition due to uniformity of the currentdensity across the single large electrode which is typically employed inconventional platers.

5. Various structures are currently disclosed in the prior art oremployed in carrying out metallizing process, such as the electrolyticdeposition onto a substrate of metallic materials, for example, such ascopper in order to produce electrolytic copper foils through theemployment of a rotating cathode drum and an anode or plurality ofsub-anodes which are located opposite the cathode drum.

6. Kubo, et al., U.S. Pat. No. 5,326,455 discloses a method and anapparatus for the production of electrolytic copper foil, wherein theapparatus utilizes a bath rather than one or more fluid heads forplating the foil, or alternatively employs a plurality of anodes with asingle fluid head. The individual anodes can be controlled with respectto the quantity of electricity being supplied so as to provide for auniform electrolytic deposition of a metallic material across the foilsurface. Erickson et al., U.S. Pat. No. 5,389,214 discloses a fluidtreatment system, wherein electrically reconfigurable electrodearrangements are employed, and in which a controller alters theeffective separation area between the active electrode in response toresistivity variations so as to provide an optimal operation of thesystem. There is no workpiece provided for effectuating electrolyticdeposition of metallic material, but rather the disclosure is directedto the treatment of fluids.

7. Blasing, et al., U.S. Pat. No. 5,292,424 pertains to a method forcontrolling a work cycle in electroplating plants, wherein differentlevels of electrical currents are applied to a series of adjacentlylocated electrodes. This structure is similar in operation to Kubo, etal., U.S. Pat. No. 5,326,455 due to the utilization of baths in order toderive the electrolytic deposition of the metallic materials.

8. Komoto, et al., U.S. Pat. Nos. 4,749,460 and 4,765,878, each providefor an apparatus for electrolytic plating wherein the plating currentsof a plurality of successive plating cells are automatically controlledin accordance with specific conditions in order to maintain uniformthickness of the metallic material which is being deposited onto asubstrate.

9. Saprokhin, et al., U.S. Pat. No. 4,511,440 discloses a process forthe electrolytic production of fluorine; however, in which there is noindividual control of an electrical power supply to anodes. Furthermore,there is no disclosure of any workpiece which is coated through thedeposition of a metallic material by means of electrolytic platingoperation, and this publication is merely directed to the production offluorine gas.

10. Schober, U.S. Pat. No. 4,164,454 discloses a continuous line forplating on intermittent lengths of metallic strip material, whereinworkpieces are moved past a plating apparatus with no provision beingmade for any individual control of a supply of electrical current to theanodes.

SUMMARY OF THE INVENTION

11. In essence, none of the prior art publications as set forthhereinabove disclose a novel and inventive concept which is directed toincorporating the advantages of currently employed fluid head technologyinto the implementation an electrolytic metallization, coating oretching process, or electrolytic plating, which would ordinarily not beconsidered to be possible to effectuate. Basically, the invention isdirected to the provision of an external transport system wherein acathode drum brush for supplying electrical current and a drive wheel ofa substrate transport system are in intimate contact with comments orhardware which is to be processed, such as printed circuit boards or thelike, thereby facilitating continuous electrical contact with thecomponents being processed which conveyed through the transport system,or fluid head during any specific period of time.

12. Pursuant to the invention there is disclosed an electricallyconductive brush and drive wheel on opposite side edges of the workpiecebeing processed, which in essence contacts the workpiece enablingindividual sheets or continuous rolls or webs to be processed duringconveyance through transport system, the latter of which may comprise afluid head, and by using the cathode brush and drive wheel for workpiececonveyance and for supplying electrical current.

13. In connection with the foregoing, the invention is directed to theprovision of an electrolytic plating apparatus which includes afluid-containing head having a fluid input; an arrangement to moveworkpieces past the fluid head, with a plurality of anodes being locatedwithin the head, each anode being individually controllable in itselectrical potential in order to provide a specific electrical fieldstrength at different positions of the workpiece, while the workpiece ismoving past the fluid head. In particular, the brush cathode and thedrive wheel which are located externally of the transport system, suchas the fluid head, are at all times physical and electrical contact withthe workpiece during the electrolytic plating procedure, so as tomaintain a constant electrical potential therewith.

14. By utilizing the concepts of the present invention, it isconsequently possible to produce an electrolytic metallization anddeposition system that can alleviate essentially all of the problemsnormally associated with conventional systems, which are incurred whenattempting to manufacture printed circuit boards of various dimensions,as well as differences in circuit densities on the same process line.

15. Pursuant to the inventive structure, banks of anodes (or cathodes)are situated within the fluid head body such that at any given timeeither all or only specific areas within the working dimensions of thedevice can be activated from a keyboard control station. This allows forcontinuous operation of the system with only momentary interruptions forresetting the “active” area within the system. Compensation forextremely dense as well as very sparse areas of circuitry on the samepanel or circuit board can be adjusted for, a feature not attainable onconventional systems. Thus, by employing the inventive concept, panelsize and variations of circuit density no longer present any problem.

16. This concept system can be utilized for any type of electrochemicaldeposition process. Examples would be for CU, NI and AU, as well as anyother metals. It can also be used to enhance coating operations, such aselectrophoretic deposition processes. Another use would be to enhanceelectrochemical etching techniques, essentially anything that wouldrequire a potential in order to be deposited or etched away from asubstrate.

17. Accordingly, it is an object of the present invention to provide anapparatus comprising a transport system for conveying a workpiece forthe purpose of implementing electrolytic metallization or deposition,including a plurality of anodes each individually controllable to anelectrical potential, and with a brush cathode and drive wheelarrangement being in contact with the workpiece at all times duringelectrolytic plating.

18. A further object of the invention resides in the provision of atransport system as described herein which comprises a fluid head havinga fluid input, with the transport system being able to move theworkpiece past the fluid head, and wherein the brush cathode and thedrive wheel structure for conveying the work piece are locatedexternally of the fluid head and are in constant contact with theworkpiece so as to be able to apply a constant electrical potentialthereto.

19. Another object of the present invention resides in the provision ofa method for making and maintaining electrical contact with a productbeing processed in a transport system utilizing a cathode brush anddrive wheel for conveyance and concurrent electrical conduction, andwith a plurality of anodes being selectively activatable in order tomaintain predetermined electroplating conditions on a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

20. Reference may now be had to the following detailed description of apreferred embodiment of the invention, taken in conjunction with theaccompanying drawings; in which:

21.FIG. 1 illustrates a generally diagrammatic perspectiverepresentation of an apparatus for electrolytically producing anelectrolytic copper foil, pursuant to the current state-of-the-art;

22.FIG. 2 illustrates a perspective front elevational view of aninventive selective electrode plating arrangement for electrolyticmetallization or deposition on a substrate; and

23.FIG. 3 illustrates, generally diagrammatically, a side elevationalview of the arrangement of FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

24. Reverting in particular to FIG. 1 of the drawings, illustrating anapparatus 10 for producing electrolytic depositions of metallicmaterial, such as copper which is employed in the forming of anelectrolytic copper foil 12. In that instance, there is illustrated anencoder 14 which determines the angular rotation of a cathode drum 16,wherein the drum is partially immersed in an electrolytic solution. Aplurality of sub-anodes 18 are spaced across the width of the drum 16,each of which is adapted to be imparted a selected electric currentdensity. A suitable calculator 20 computes deviations in the measuredthickness of the intended foil thickness of the target foil, andtransmits such information as to variations to a rectifier controller22, which also receives angle information from the encoder 14. Thecurrent or quantities of electricity supplied to the various sub-anodeswhich are spaced across the width of the drum 16 is controlled byassociated sub-rectifiers 24 in order to provide an increase or decreasein current supplied thereto so as to enable control over the uniformityin the thickness of the metallic or copper foil which is being produced.In essence, the prior art structure as described above, which isessentially that of the Kubo, et al., U.S. Pat. No. 5,326,455, disclosesan electrolytic deposition apparatus in the form of a bath, whereas itis also possible to provide for a fluid-containing anode drum or fluidhead having a plurality of a small electrodes, such as sub-anodes,spaced across the width thereof.

25. However, in accordance with the invention, in order to contemplate aunique and versatile construction of a selective electrolyticmetallization/deposition apparatus 30 which enables obtaining furtheradvantages while utilizing presently known fluid head technology in theimplementing of electrolytic metallization, coating, plating and etchingprocesses, there is provided a transport arrangement or installation 32,which, if desired, may be of a fluid-containing head design, as shown inFIGS. 2 and 3 of the drawings.

26. A plurality of anodes are in the form of linear arrays or banks ofsub-anodes 34, 36 which are, respectively, located on opposite sides ofa product which is being conveyed by the transport arrangement 32. Theproduct may be either a continuous roll or web W forming the substratewhich is to be imparted a metallized coating or deposition, or may beconstituted of discrete components advanced in succession, such ascircuit boards. Each array of sub-anodes extends across substantially amajor portion of the width of the product W with each sub-anode 34 beingconnected to anode power switch 40, and sub-anodes 36 being connectedanode power switch 42. In turn, the anode power switches 38, 40 areconnected to a suitable electrical power supply 42, with the power beingselective to the various sub-anodes in order to provide a uniform degreeof deposition of metal across the surface of the product beingprocessed.

27. In order to attain the inventive object, the transport arrangement32 comprises an external transport mechanism which, in this instance,consist of a drive motor 46 for driving a pair cooperative wheels 48, 50engaging opposite surfaces along the one longitudinal edge 52 of theproduct W being processed. Also similar contacted by upper and lowerwheels 54, 56 is the opposite edge 58 of the product, so as to conveythe product consisting of the foil or sheets W through the transportarrangement at a predetermined rate of advancing speed. Each of thewheels 48, 50, 54, 56 contacting respectively the upper and lowersurfaces of the product is respectively, in electrical contact with acathode brush 60, 62, 64, 66 which, in turn, is connected to the powersupply 42 which also supplies the sub-anodes with electrical current,and ensures that the product W is always in electrical contact with thecathode brushes with the wheel 50 being a cathode drive wheel.

28. As illustrated, in further detail in FIG. 3 of the drawings, thetransport arrangement 32, in that instance, includes a fluid-containingfluid head 70 which has a nitrogen curtain input 72 connected to a sump74 and pump system 76 for electrolyte, with the sub-anode electrodesshown in FIG. 3 of the drawings. The nitrogen curtain input is providedat the locations illustrated whereby the entire system advantageouslyfacilitates the continuous electrical contact of the product W by thecathode brushes in operative conjunction with the selectively actuatedor controllable power-supplied sub-anodes extending in arrays acrossrespectively the upper and lower surfaces of the product. This willprovide an improved metallization and deposition performance while alsoenabling fabrication to be implemented continuously. The continuouselectrical contact provided for by the cathode brushes enables theentire apparatus to provide a capability for selectivemetallization/deposition which is ordinarily impossible to attain withinthe format of currently employed fluid heads for individual circuitprocessing.

29. From the foregoing, it becomes readily apparent that the inventionis clearly directed to novel and advantageous features not at allcontemplated in the art, irrespective as to whether applied to fluidhead apparatuses, or to a product transport system providing forcontinuous electrical cathode contact with the surfaces of the productwhich is to be electrolytically metallized.

30. While there has been shown and described what is considered to be apreferred embodiment of the invention, it will, of course, be understoodthat various modifications and changes in form or detail could readilybe made without departing from the spirit of the invention. It is,therefore, intended that the invention be not limited to the exact formand detail herein shown and described, nor to anything less than thewhole of the invention herein disclosed as hereinafter claimed.

What is claimed is:
 1. An apparatus for the electrolytic metallizationof a workpiece; said apparatus comprising: (a) means for imparting anelectrolyte to said workpiece; (b) means for conveying said workpiecepast said electrolyte; (c) means connected to an electrical power supplyfor maintaining electrical contact with said workpiece being conveyedwhile avoiding exposure of said electrical contact means to saidelectrolyte; (d) a plurality of anode electrodes spaced across saidworkpiece proximate said electrolyte, said anode electrodes each beingconnected to said electrical power supply; and (e) means forindividually controlling an electrical potential across each said anodeelectrode so as to provide a specified electrical field strength atdifferent anode electrode positions across said workpiece and along thedirection of conveyance of said workpiece during transport of saidworkpiece past said electrolyte imparting means.
 2. An apparatus asclaimed in claim 1 , wherein said workpiece conveying means comprisecooperating pairs of wheels drivingly contacting opposite side edges ofsaid workpiece; and a drive motor being connected to at least one ofsaid pairs of wheels to advance said workpiece through said apparatus.3. An apparatus as claimed in claim 2 , wherein said pairs of drivewheels are in electrical communication with said electrical power supplyfor maintaining an electrical potential on said workpiece.
 4. Anapparatus as claimed in claim 3 , wherein said pairs of wheels each formcathode electrodes contacting said workpiece, said wheels each beingcontinuously contacted by a cathode brush which is electricallyconnected to said electrical power supply.
 5. An apparatus as claimed inclaim 1 , wherein said anode electrodes extend in linear arrays aboveand below said workpiece; and power control switch means being connectedto each of said anode electrodes for selectively controlling theelectrical potential of each of said anode electrodes.
 6. An apparatusas claimed in claim 1 , wherein said electrolyte comprises ametal-containing fluid.
 7. An apparatus as claimed in claim 6 , whereinsaid electrolyte comprises electrolytic copper.
 8. An apparatus asclaimed in claim 6 , wherein said electrolyte comprises nickel.
 9. Anapparatus as claimed in claim 6 , wherein said electrolyte comprisesgold.
 10. An apparatus as claimed in claim 1 , wherein said workpiece isconstituted of a continuous web which is conveyed through saidapparatus.
 11. An apparatus as claimed in claim 1 , wherein saidworkpiece comprises a panel forming a substrate for electricalcircuitry.
 12. An apparatus for the electrolytic metallization of aworkpiece; said apparatus comprising: (a) fluid head means for impartingan electrolyte to said workpiece; (b) means for conveying said workpiecepast said fluid head means; (c) means connected to an electrical powersupply for maintaining electrical contact with said workpiece beingconveyed while avoiding exposure of said electrical contact means tosaid fluid head, said electrical contact means being located externallyof said fluid head means; (d) a plurality of anode electrodes spacedacross said workpiece proximate said fluid head, said anode electrodeseach being connected to said electrical power supply; and (e) means forindividually controlling an electrical potential across each said anodeelectrode so as to provide a specified electrical field strength atdifferent anode electrode positions across said workpiece and along thedirection of conveyance of said workpiece during transport of saidworkpiece past said fluid head means.
 13. An apparatus as claimed inclaim 12 , wherein said workpiece conveying means comprise cooperatingpairs of wheels drivingly contacting opposite side edges of saidworkpiece externally of said fluid head means; and a drive motor beingconnected to at least one of said pairs of wheels to advance saidworkpiece through said apparatus.
 14. An apparatus as claimed in claim13 , wherein said pairs of drive wheels are in electrical communicationwith said electrical power supply for maintaining an electricalpotential on said workpiece.
 15. An apparatus as claimed in claim 14 ,wherein said pairs of wheels each form cathode electrodes contactingsaid workpiece, said wheels each being continuously contacted by acathode brush which is electrically connected to said electrical powersupply.
 16. An apparatus as claimed in claim 12 , wherein said anodeelectrodes extend in linear arrays above and below said workpiece; andpower control switch means are connected to each of said anodeelectrodes for selectively controlling the electrical potential of eachof said anode electrodes.
 17. An apparatus as claimed in claim 12 ,wherein said workpiece is constituted of a continuous web which isconveyed through said fluid head means.
 18. An apparatus as claimed inclaim 12 , wherein said workpiece comprises a panel forming a substratefor electrical circuitry.
 19. A method for the electrolyticmetallization of a workpiece; said method comprising: (a) imparting anelectrolyte to said workpiece; (b) conveying said workpiece past saidelectrolyte; (c) an electrical power supply for maintaining electricalcontact with said workpiece while avoiding exposure of said electricalcontact means to said electrolyte; (d) spacing a plurality of anodeelectrodes across said workpiece proximate said electrolyte, said anodeelectrodes each being connected to said electrical power supply; and (e)individually controlling an electrical potential across each said anodeelectrode so as to provide a specified electrical field strength atdifferent anode electrode positions across said workpiece and along thedirection of conveyance of said workpiece during transport of saidworkpiece past said electrolyte imparting means.
 20. A method as claimedin claim 19 , wherein said workpiece conveying is effected bycooperating pairs of wheels drivingly contacting opposite side edges ofsaid workpiece; and a drive motor being connected to at least one ofsaid pairs of wheels to advance said workpiece through said apparatus.21. A method as claimed in claim 20 , wherein said pairs of drive wheelsare in electrical communication with said electrical power supply formaintaining an electrical potential on said workpiece.
 22. A method asclaimed in claim 21 , wherein said pairs of wheels each form cathodeelectrodes contacting said workpiece, said wheels each beingcontinuously contacted by a cathode brush which is electricallyconnected to said electrical power supply.
 23. A method as claimed inclaim 19 , wherein said anode electrodes extend in linear arrays aboveand below said workpiece; and power control switches are connected toeach of said anode electrodes for selectively controlling the electricalpotential of each of said anode electrodes.
 24. A method as claimed inclaim 19 , wherein said electrolyte comprises a metal-containing fluid.25. A method as claimed in claim 24 , wherein said electrolyte compriseselectrolytic copper.
 26. A method as claimed in claim 24 , wherein saidelectrolyte comprises nickel.
 27. A method as claimed in claim 24 ,wherein said electrolyte comprises gold.
 28. A method as claimed inclaim 19 , wherein said workpiece is constituted of a continuous webwhich is conveyed through said apparatus.
 29. A method as claimed inclaim 19 , wherein said workpiece comprises a panel forming a substratefor electrical circuitry.
 30. A method for the electrolyticmetallization of a workpiece; said method comprising: (a) providing afluid head for imparting an electrolyte to said workpiece; (b) conveyingsaid workpiece past said fluid head; (c) connecting an electrical powersupply for maintaining electrical contact with said workpiece whileavoiding exposure of said electrical contact means to said fluid head byforming said electrical contact externally of said fluid head; (d)spacing a plurality of anode electrodes across said workpiece proximatesaid fluid head, said anode electrodes each being connected to saidelectrical power supply; and (e) individually controlling an electricalpotential across each said anode electrode so as to provide a specifiedelectrical field strength at different anode electrode positions acrosssaid workpiece and along the direction of conveyance of said workpieceduring transport of said workpiece past said fluid head.
 31. A method asclaimed in claim 30 , wherein said workpiece conveying is effected bycooperating pairs of wheels drivingly contacting opposite side edges ofsaid workpiece; and a drive motor being connected to at least one ofsaid pairs of wheels to advance said workpiece through said apparatus.32. A method as claimed in claim 31 , wherein said pairs of drive wheelsare in electrical communication with said electrical power supply formaintaining an electrical potential on said workpiece.
 33. A method asclaimed in claim 32 , wherein said pairs of wheels each form cathodeelectrodes contacting said workpiece, said wheels each beingcontinuously contacted by a cathode brush which is electricallyconnected to said electrical power supply.
 34. A method as claimed inclaim 30 , wherein said anode electrodes extend in linear arrays aboveand below said workpiece; and power control switches are connected toeach of said anode electrodes for selectively controlling the electricalpotential of each of said anode electrodes.